Brazing refers to a technique for joining two base metals by applying heat at such a level as not to damage a base metal with a separate metal or alloy having a melting point lower than that of the metal (base metal) molten.
In the brazing, joining (soldering) is performed by using a brazing alloy containing silver and the soldering has been used as an important means in various industrial fields such as a cooling and heating apparatus and the like. For example, soldering is widely used for piping equipment of a typical cooling and heating apparatus or refrigeration equipment.
Further, soldering is used for coupling copper pipe parts or brass parts to a copper pipe and is classified as brazing (hard soldering) and soldering (soft soldering) according to a working temperature. Particularly, the brazing, which is a method of bringing metals into contact to be held together without melting base metals at a working temperature of about 400 to 900° C., is a joining method for forming a strong and tight weld junction between two metals. Therefore, the brazing is used variously for coupling same or similar metals and dissimilar metals, coupling a thick portion and a thin portion, or coupling metals having greatly different melting points.
Particularly, when welding a brass material, if a working temperature increases or a working time lengthens, dezincification occurs on the surface of brass, resulting in generating scales. Since the generated scale obstructs the flow of the welding material, there is a problem in that an oxide needs to be removed during welding by using a flux aid (for example, a gas flux, chlorides, fluorides, boron compounds, and the like).
Currently, silver (Ag) is ineluctably used as an alloy component for solving the problem. Particularly, in a pipe welding field, a material containing 0.5 to 30 wt % of silver (Ag) is used as a welding material when welding brass parts. The reason for adding the silver (Ag) is to improve flow-ability, wet-ability, and adhesiveness on the surface of brass while lowering a melting point.
However, the silver (Ag) is a high-priced precious metal and thus a cost thereof is expected to continue to increase in consideration of the future development trend of an electronic industry or the like. Therefore, in the economic aspect, there is a need to use no high-priced silver or minimize the silver (Ag) content and from the viewpoint of weldability, a brazing alloy capable of further improving a self-fluxing function of a brazing alloy and the affinity between metals is required.